const fp = require('lodash/fp')
// 数据
// hoursepower 马力，dollar_value 价格 in_stock 库存
const cars = [{
    name: 'Ferrari FF',
    hoursepower: 660,
    dollar_value: 700000,
    in_stock: true
}, {
    name: 'Spyker C12 Zagato',
    hoursepower: 650,
    dollar_value: 648000,
    in_stock: false
}, {
    name: 'Jaguar XKR-S',
    hoursepower: 550,
    dollar_value: 132000,
    in_stock: false
}, {
    name: 'Audi R8',
    hoursepower: 525,
    dollar_value: 114200,
    in_stock: false
}, {
    name: 'Aston Martin One-77',
    hoursepower: 750,
    dollar_value: 1850000,
    in_stock: true
}, {
    name: 'Pagani Huayra',
    hoursepower: 700,
    dollar_value: 1300000,
    in_stock: false
}]

//练习1：使用函数组合fp.flowRight()重新实现下面这个函数
let isLastInStock = function (cars) {
    let last_car = fp.last(cars)
    return fp.prop('in_stock', last_car)
}
//EX1
let isLastInStock2 = fp.flowRight(fp.prop('in_stock'), fp.last)
//EX1 Test
console.log(isLastInStock(cars))
console.log(isLastInStock2(cars))

//练习2：使用fp.flowRight()、fp.prop()和fp.first()获取第一个car的name
//EX2
let firstCarName = fp.flowRight(fp.prop('name'), fp.first)
//EX2 Test
console.log(firstCarName(cars))

//练习3：使用帮助函数_average重构averageDollarValue，使用函数组合的方式实现
let _average = function (xs) {
    return fp.reduce(fp.add, 0, xs) / xs.length
}
let averageDollarValue = function (cars) {
    let dollar_values = fp.map(car => car.dollar_value, cars)
    return _average(dollar_values)
}
//EX3
let averageDollarValue2 = fp.flowRight(_average, fp.map(car => car.dollar_value))
//EX3 Test
console.log(averageDollarValue2(cars))

//- 练习4：使用flowRight写一个sanitizeNames()函数，返回一个下划线连接的小写字符串，把数组中的name转换为这种形式：例如：sanitizeNames(['Hello World']) => ["hello_world"]
let _underscore = fp.replace(/\W+/g, '_')
//EX4
let sanitizeNames = fp.flowRight(fp.map(fp.flowRight(fp.toLower, _underscore)), fp.map(item => item.name))
//EX4 Test
console.log(sanitizeNames(cars))